Electrosurgical system

ABSTRACT

An electrosurgical system is provided and includes a bipolar electrosurgical instrument and an electrosurgical generator. The bipolar electrosurgical instrument is arranged to seal and cut tissue captured between jaws of the bipolar electrosurgical instrument. The electrosurgical generator is arranged to supply RF energy through the bipolar electrosurgical instrument, monitor the supplied RF energy, and adjust or terminate the supplied RF energy to optimally seal the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/674,965 entitled “Electrosurgical System” filed Nov. 5, 2019, whichclaims priority to and benefit of U.S. Provisional Patent ApplicationSer. No. 62/768,782 entitled “Electrosurgical System” filed on Nov. 16,2018, which is incorporated herein by reference in its entirety.

BACKGROUND

The present application relates generally to electrosurgical systems andmethods. More particularly, the present application relates toelectrosurgical generators and associated instruments for sealing andcutting tissue.

There are available electrosurgical devices or instruments that useelectrical energy to perform certain surgical tasks. Typically,electrosurgical instruments are surgical instruments such as graspers,scissors, tweezers, blades, and/or needles that include one or moreelectrodes that are configured to be supplied with electrical energyfrom an electrosurgical generator. The electrical energy can be used tocoagulate, fuse, or cut tissue.

Electrosurgical instruments typically fall within two classifications:monopolar and bipolar. In monopolar instruments, electrical energy issupplied to one or more electrodes on the instrument with high currentdensity while a separate return electrode is electrically coupled to apatient. The separate return electrode is often designed to minimizecurrent density. Monopolar electrosurgical instruments can be useful incertain procedures but can include a risk of certain types of issuessuch as electrical burns that may be partially attributable to thefunctioning of the return electrode.

In bipolar electrosurgical instruments, one or more electrodes areelectrically coupled to a source of electrical energy of a firstpolarity. In addition, one or more other electrodes are electricallycoupled to a source of electrical energy of a second polarity oppositethe first polarity. Bipolar electrosurgical instruments, which operatewithout separate return electrodes, can deliver electrical signals to afocused tissue area with reduced risks compared to monopolarelectrosurgical instruments.

Even with the relatively focused surgical effects of bipolarelectrosurgical instruments surgical, however, outcomes are often highlydependent on surgeon skill. For example, thermal tissue damage andnecrosis can occur in instances where electrical energy is delivered fora relatively long duration or where a relatively high-powered electricalsignal is delivered even for a short duration. The rate at which atissue will achieve the desired fusing, sealing, or cutting effect uponthe application of electrical energy varies based on the tissue type andcan also vary based on pressure applied to the tissue by anelectrosurgical device. However, it can be difficult for a surgeon toassess how quickly a mass of combined tissue types grasped in anelectrosurgical instrument will be sealed a desirable amount.

SUMMARY OF THE INVENTION

Disclosed herein are methods, devices, and systems for fusing or sealingtissue. In a first embodiment, a method for fusing or sealing tissue isdescribed. The method begins by first applying a first amount of RFenergy to an area of tissue. A desiccation level of the area of tissueaffected by the first amount of RF energy is then determined. Based onthe determined desiccation level, the amount of RF energy is reduced toa second amount. Subsequent to reducing to the second amount of RFenergy, an increasing amount of RF energy is applied to the area oftissue until a third amount is reached. A rate by which the RF energy isadded and the third amount is based on the determined desiccation level.The third amount of RF energy is applied to the area of tissue for apre-determined period of time. Once the pre-determined period of timehas elapsed, the application of the RF energy to the area of tissue isterminated.

In another embodiment, an electrosurgical generator used for fusing orsealing tissue is described. The electrosurgical generator includes acontroller and an RF amplifier that generates a corresponding amount ofRF energy based on the instructions provided by the controller. Thecontroller first instructs the RF amplifier to apply a first amount ofRF energy to an area of tissue. The controller then determines adesiccation level of the area of tissue affected by the first amount ofRF energy. The controller then instructs the RF amplifier to firstreduce the amount of RF energy to a second amount based on thedetermined desiccation level and subsequently increase an amount of RFenergy being applied to the area to a third amount. A rate by which theRF energy is added and the third amount is based on the determineddesiccation level. The controller instructs the RF amplifier to maintainthe third amount of RF energy being applied to the area of tissue for apre-determined period of time. Once the pre-determined period of timehas elapsed, the controller instructs the RF amplifier to terminate theapplication of the RF energy to the area of tissue.

In another embodiment, a system for fusing or sealing tissue isdescribed. The system includes an electrosurgical generator thatgenerates RF energy and an electrosurgical instrument that fuses orseals an area of tissue. The electrosurgical instrument receives the RFenergy from the electrosurgical generator in order to fuse or seal thearea of tissue. The amount of RF energy that is generated and providedto the electrosurgical instrument to use in the fusing or sealing of thearea of tissue is based on a determined desiccation level of the area oftissue.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner which, the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles briefly described above will berendered by reference to specific embodiments that are illustrated inthe appended drawings. Understanding that these drawings depict onlyembodiments of the disclosure and are not therefore to be considered tobe limiting of its scope, the principles herein are described andexplained with additional specificity and detail through the use of theaccompanying drawings in which the reference numerals designate likeparts throughout the figures thereof.

FIG. 1 is a perspective view of an electrosurgical system in accordancewith various embodiments of the present invention.

FIG. 2 and FIG. 3 are perspective views of an electrosurgical instrumentin accordance with various embodiments of the present invention.

FIG. 4 to FIG. 7 are graphical representations of samples ofexperimental data for a sealing process or aspects thereof with anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIG. 8 is a schematic block diagram of portions of an electrosurgicalsystem in accordance with various embodiments of the present invention.

FIG. 9 is a graphical representation of samples of experimental data fora sealing process or aspects thereof with an electrosurgical system inaccordance with various embodiments of the present invention.

FIG. 10 is a flowchart illustrating operations of an electrosurgicalsystem in accordance with various embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with various embodiments, an electrosurgical instrument isprovided that is configured to fuse and cut tissue. In variousembodiments, the electrosurgical device or instrument includes a firstjaw and a second jaw. The second jaw opposes the first jaw to facilitatethe grasping of tissue between the first jaw and the second jaw. Boththe first jaw and the second jaw include an electrode. The electrodes ofthe first jaw and the second jaw are arranged to seal tissue graspedbetween the first jaw and the second jaw using radio frequency (RF)energy.

In accordance with various embodiments, an electrosurgical system forsealing tissue is also provided. The electrosurgical system in variousembodiments comprises an electrosurgical generator and anelectrosurgical instrument or device. The electrosurgical generatorincludes an RF amplifier and a controller. The RF amplifier supplies RFenergy through a removably coupled electrosurgical instrument configuredto seal tissue with only RF energy. The controller and/or RF sense arearranged to monitor and/or measure the supplied RF energy and/orcomponents thereof. In various embodiments, the controller signals theRF amplifier to adjust, e.g., increase, hold, decrease and/or stop,voltage of the supplied RF energy at predetermined points or conditionsof a sealing cycle. In various embodiments, the controller signals theRF amplifier to halt the supplied RF energy or initiate termination ofthe supplied RF energy from the RF amplifier.

The various features and embodiments provided throughout can be usedalone, or in combination with other features and/or embodiments otherthan as expressly described and although specific combinations ofembodiments and features or aspects of various embodiments may not beexplicitly described such combinations however are contemplated andwithin the scope of the present inventions. Many of the attendantfeatures of the present inventions will be more readily appreciated asthe same becomes better understood by reference to the foregoing andfollowing description and considered in connection with the accompanyingdrawings.

Generally, an electrosurgical system is provided that includes anelectrosurgical generator and a removably coupled electrosurgicalinstrument that are configured to optimally seal or fuse tissue. The RFenergy is supplied by the electrosurgical generator that is arranged toprovide the appropriate RF energy to seal the tissue. Theelectrosurgical generator, in accordance with various embodiments,determines the appropriate RF energy and the appropriate manner todeliver the RF energy for the particular connected electrosurgicalinstrument, the particular tissue in contact with the electrosurgicalinstrument, and/or a particular surgical procedure being performed.Operationally, RF sealing or fusing of tissue between the jaws isprovided to decrease sealing time and/or thermal spread.

In accordance with various embodiments, the electrosurgical systemcomprises a dynamic pulse system arranged to control and shut off RFenergy delivery that results in an optimal balance of hemostasisreliability, seal time, and tissue adherence for a wide range oftissues. In various embodiments, the electrosurgical system comprises adouble or repeat seal system arranged to reduce the application of RFenergy for multiple activations to reduce eschar (sealed tissue debris)buildup, tissue adherence, and thermal spread for tissue that is alreadysealed.

Referring to both FIG. 1 and FIG. 2 , an exemplary embodiment of theelectrosurgical system is illustrated. The electrosurgical systemincludes an electrosurgical generator 10 (as illustrated in FIG. 1 ) anda removably connectable electrosurgical instrument 20 (as illustrated inFIG. 2 ). The electrosurgical instrument 20 can be electrically coupledto the electrosurgical generator 10 via a cabled connection 30 having anadaptor 32 configured to connect to a tool or device port 12 on theelectrosurgical generator 10. The electrosurgical instrument 20 mayinclude audio, tactile and/or visual indicators to apprise a user of aparticular predetermined status of the electrosurgical instrument 20such as a start and/or end of a fusion or cut operation. In otherembodiments, the electrosurgical instrument 20 can be reusable and/orconnectable to another electrosurgical generator for another surgicalprocedure. In some embodiments, a manual controller such as a hand orfoot switch can be connectable to the electrosurgical generator 10and/or electrosurgical instrument 20 to allow predetermined selectivecontrol of the electrosurgical instrument 20 such as to commence afusion or cut operation.

In accordance with various embodiments, the electrosurgical generator 10is configured to generate radio frequency (RF) electrosurgical energyand to receive data or information from the electrosurgical instrument20 electrically coupled to the electrosurgical generator 10. Theelectrosurgical generator 10, in one embodiment, outputs RF energy(e.g., 375 VA, 150V, 5 A at 350 kHz) and in one embodiment is configuredto measure current and/or voltage of the RF energy and/or to calculatepower of the RF energy or a phase angle or difference between RF outputvoltage and RF output current during activation or supply of the RFenergy. The electrosurgical generator 10 regulates voltage, currentand/or power and monitors the RF energy output (e.g., voltage, current,power and/or phase). In one embodiment, the electrosurgical generator 10stops the RF energy output under predefined conditions such as when adevice switch is de-asserted (e.g., fuse button released), a time valueis met, and/or active phase angle, current, voltage or power and/orchanges thereto is greater than, less than or equal to a stop value,threshold or condition and/or changes thereto.

As illustrated in FIG. 1 , the electrosurgical generator 10 comprises atleast one advanced bipolar tool port 12, a standard bipolar tool port16, and an electrical power port 14. In other embodiments,electrosurgical units can comprise different numbers of ports. Forexample, in some embodiments, an electrosurgical generator 10 cancomprise more or fewer than two advanced bipolar tool ports, more orfewer than the standard bipolar tool port, and more or fewer than thepower port. In one embodiment, the electrosurgical generator 10comprises only two advanced bipolar tool ports.

In accordance with various embodiments, each advanced bipolar tool port12 is configured to be coupled to an advanced electrosurgical instrumenthaving an attached or integrated memory module. The standard bipolartool port 16 is configured to receive a non-specialized bipolarelectrosurgical tool that differs from the advanced bipolarelectrosurgical instrument connectable to the advanced bipolar tool port12. The electrical power port 14 is configured to receive or beconnected to a direct current (DC) accessory device that differs fromthe non-specialized bipolar electrosurgical tool and the advancedelectrosurgical instrument. The electrical power port 14 is configuredto supply direct current voltage. For example, in some embodiments, theelectrical power port 14 can provide approximately 12 Volts DC. Theelectrical power port 14 can be configured to power a surgicalaccessory, such as a respirator, pump, light, or another surgicalaccessory. Thus, in addition to replacing the electrosurgical generator10 for standard or non-specialized bipolar tools, the electrosurgicalgenerator 10 can also replace a surgical accessory power supply. In someembodiments, replacing presently-existing generators and power supplieswith the electrosurgical generator 10 can reduce the amount of storagespace required on storage racks cards or shelves and reduce the numberof main power cords required in a surgical workspace.

In accordance with various embodiments, the electrosurgical generator 10can comprise a display 15. The display 15 can be configured to indicatethe status of the electrosurgical system including, among otherinformation, the status of the one or more electrosurgical instrumentsand/or accessories, connectors or connections thereto.

The electrosurgical generator 10 in accordance with various embodimentscan comprise a user interface, such as a plurality of buttons 17. Theplurality of buttons 17 can allow user interaction (e.g., receiving userinput) with the electrosurgical generator 10 such as, for example,requesting an increase or decrease in the electrical energy supplied toone or more electrosurgical instruments coupled to the electrosurgicalgenerator 10. In other embodiments, the display 15 can be a touch screendisplay thus integrating data display and user interfacefunctionalities. In one embodiment, the electrosurgical tool orinstrument 20 can further comprise of one or more memory modules. Insome embodiments, the memory comprises operational data concerning theelectrosurgical instrument and/or other instruments. For example, insome embodiments, the operational data may include information regardingelectrode configuration/reconfiguration, the electrosurgical instrumentuses, operational time, voltage, power, phase and/or current settings,and/or particular operational states, conditions, scripts, processes orprocedures. In one embodiment, the electrosurgical generator 10 caninitiate reads and/or writes to the memory module.

In accordance with various embodiments, the electrosurgical generator 10provides the capability to read the phase difference or phase anglebetween the voltage and current of the RF energy sent through theconnected electrosurgical instrument 20 while RF energy is active. Whiletissue is being fused, phase readings are used to detect differentstates during the fuse or seal and cut process.

The electrosurgical generator 10 in accordance with various embodimentsmonitors, measures or calculates current, power, impedance or phase ofthe RF output, but does not control current, power, impedance or phase.The electrosurgical generator 10 regulates voltage and can also adjustvoltage. Electrosurgical power delivered is a function of appliedvoltage, current, and tissue impedance. The electrosurgical generator10, through the regulation of voltage, can affect the electrosurgicalpower, RF output, or energy being delivered. Power reactions are causedby the power interacting with the tissue or the state of the tissuewithout any control by a generator other than by the generator supplyingpower.

Once the electrosurgical generator 10 starts to deliver electrosurgicalpower, the electrosurgical generator 10 continues to do so continuously,e.g., for 150 ms, until a fault occurs or until a specific parameter isreached. In one example, the jaws of the electrosurgical instrument canbe opened and thus compression relieved at any time before, during, andafter the application of electrosurgical power. The electrosurgicalgenerator 10, in one embodiment, also does not pause or wait aparticular duration or a predetermined time delay to commencetermination of the electrosurgical energy.

With additional reference to FIG. 3 , in accordance with variousembodiments, a bipolar electrosurgical instrument 20 is provided. In theillustrated embodiment, the bipolar electrosurgical instrument 20includes an actuator 24 coupled to an elongate rotatable shaft 26. Theelongate rotatable shaft 26 has a proximal end and a distal end defininga central longitudinal axis therebetween. At the distal end of theelongate rotatable shaft 26 are jaws 22 and at the proximal end is theactuator 24. In one embodiment, the actuator 24 is a pistol-grip likehandle.

The actuator 24 includes a movable handle 23 and a stationary handle orhousing 28. The movable handle 23 is coupled and movable relative to thestationary housing 28. In accordance with various embodiments, themovable handle 23 is slidably and pivotally coupled to the stationaryhousing 28. In operation, the movable handle 23 is manipulated by auser, e.g., a surgeon, to actuate the jaws, for example, selectivelyopening and closing the jaws 22.

In accordance with various embodiments, the actuator 24 includes a latchmechanism to maintain the movable handle 23 in a second position withrespect to the stationary housing 28. In various embodiments, themovable handle 23 comprises a latch arm which engages a matching latchcontained within the stationary handle or housing 28 for holding themovable handle 23 at a second or closed position. The actuator 24 invarious embodiments also comprises a wire harness that includesinsulated individual electrical wires or leads contained within a singlesheath. The wire harness can exit the stationary housing 28 at a lowersurface thereof and form part of the cabled connection 30 (asillustrated in FIG. 2 ). The wires within the harness can provideelectrical communication between the electrosurgical instrument 20 andthe electrosurgical generator 10 and/or accessories thereof.

In various embodiments, a switch is connected to a user manipulatedactivation button 29 and is activated when the activation button 29 isdepressed. In one aspect, once activated, the switch completes a circuitby electrically coupling at least two leads together. As such, anelectrical path is then established from an electrosurgical generator 10to the actuator 24 to supply RF energy to the electrosurgical instrument20. In various embodiments, the electrosurgical instrument 20 comprisesa translatable mechanical cutting blade that can be coupled to a bladeactuator such as a blade lever or trigger 25 of the actuator 24. Themechanical cutting blade is actuated by the blade trigger 25 to dividethe tissue between the jaws 22.

In one embodiment, the actuator 24 includes an elongate rotatable shaft26 assembly that includes a rotation knob 27 which is disposed on anouter cover tube of the elongate rotatable shaft 26. The rotation knob27 allows a surgeon to rotate the elongate rotatable shaft 26 of theelectrosurgical instrument 20 while gripping the actuator 24. Inaccordance with various embodiments, the elongate rotatable shaft 26comprises an actuation tube coupling the jaws 22 with the actuator 24.

Attached to the distal end of the elongate rotatable shaft 26 are jaws22 that comprise a first or upper jaw 31 and a second or lower jaw 33.In one embodiment, a jaw pivot pin pivotally couples the first jaw 31and the second jaw 33 and allows the first jaw 31 to be movable andpivot relative to the second jaw 33. In various embodiments, one jaw isfixed with respect to the elongate rotatable shaft 26 such that theopposing jaw pivots with respect to the fixed jaw between an open and aclosed position. In other embodiments, both the first jaw 31 and thesecond jaw 33 can be pivotally coupled to the elongate rotatable shaft26 such that both the first jaw 31 and the second jaw 33 can pivot withrespect to each other.

The first or upper jaw 31 includes an electrode plate or pad. Similarly,the second or lower jaw 33 also includes an electrode plate or pad. Theelectrode of the first or upper jaw 31 and the electrode of the secondor lower jaw 33 are electrically coupled to the electrosurgicalgenerator 10 via wires and connectors to supply RF energy to tissuegrasped between the electrodes of the first jaw 31 and the second jaw33. The electrodes, as such, are arranged to have opposing polarity andto transmit the RF energy therebetween. The first or upper jaw 31 invarious embodiments also includes an upper jaw support with an assemblyspacer positioned between the upper jaw support and the electrode. Thefirst or upper jaw 31 also includes an overmold or is overmolded. Thesecond or lower jaw 33 can also include a lower jaw support and theelectrode. In the illustrated embodiment, the electrode is integrated orincorporated in the lower jaw support and thus the lower jaw support andthe electrode form a monolithic structure and electrical connection. Ablade channel extends longitudinally along the length of the first orupper jaw 31, the second or lower jaw 33, or both through which theblade operationally traverses. Surrounding a portion of the bladechannel are one or more conductive posts. The conductive posts assist inimmobilizing the tissue to be cut. The conductive posts also assist inensuring the tissue being cut adjacent or proximate to the blade channelis fused as the conductive posts also participate in the transmission ofRF energy to the tissue grasped between the jaws 22. The second or lowerjaw 33 can also include an overmold or is overmolded.

In accordance with various embodiments, the electrodes have a generallyplanar sealing surface arranged to contact and compress tissue capturedbetween the jaws 22. The electrodes of the first or upper jaw 31 andsecond or lower jaw 33 in various embodiments have a seal surface inwhich the width of the seal surface is uniform, constant, or remainsunchanged throughout.

In various embodiments, the jaws 22 are curved to increase visualizationand mobility of the jaws 22 at the targeted surgical site and during thesurgical procedure. The jaws 22 have a proximal elongate portion that isdenoted or aligned with straight lines and a curved distal portiondenoting or defining a curve that is connected to the straight lines. Invarious embodiments, the proximal most portion of the proximal elongateportion has or delimits a diameter that equals or does not exceed amaximum outer diameter of the jaws 22 or elongate rotatable shaft 26.The jaws 22 in various embodiments have a maximum outer diameter inwhich the proximal most portion of the jaw 22 and the distal mostportion of the jaws 22 remains within the maximum outer diameter. Thecurved distal portion has or delimits a diameter that is smaller thanthe maximum outer diameter and the diameter of the proximal most portionof the proximal elongate portion. In various embodiments, the jaw 22 hasa deeper inner curve cut-out than the outer curve and in variousembodiments the tip of the jaws 22 are tapered for blunt dissection. Thejaws 22 include a blade channel having an proximal elongate channelcurving to a distal curved channel in which the proximal elongatechannel is parallel and offset to the longitudinal axis of the elongaterotatable shaft 26 of the electrosurgical instrument 20. As such,visibility and mobility at the jaws 22 are maintained or enhancedwithout increasing jaw dimensions that may further reduce the surgicalworking area or require larger access devices or incisions into thepatient's body.

In some embodiments, electrode geometry of the conductive pads of thejaw assembly ensures that the sealing area or surface completelyencloses the distal portion of the cutting path. In accordance withvarious embodiments, the dimensions of the jaw surfaces are such that itis appropriately proportioned with regards to the optimal pressureapplied to the tissue between the jaws 22 for the potential force theforce mechanism can create. Its surface area is also electricallysignificant with regards to the surface area contacting the tissue. Thisproportion of the surface area and the thickness of the tissue have beenoptimized with respect to its relationship to the electrical relativeproperties of the tissue.

In various embodiments, the second or lower jaw 33 and an associatedconductive pad have an upper outer surface arranged to be in contactwith tissue. The upper surfaces are angled or sloped and mirror imagesof each other with such positioning or orientation facilitating focusedcurrent densities and securement of tissue. In various embodiments, thesecond or lower jaw 33 is made of stainless steel and is as rigid as ormore rigid than the conductive pad. In various embodiments, the secondor lower jaw 33 comprises rigid insulators made of a non-conductivematerial and are as rigid as or more rigid than the second or lower jaw33 or the conductive pad. In various embodiments, the second or lowerjaw 33 and the conductive pad are made of the same material.

In accordance with various embodiments, the RF energy control process orsystem supplies RF energy and controls the supplied RF energy to seal orfuse tissue. At the beginning of a seal cycle, the system is arranged toapply RF energy having a quickly increasing voltage. As such, the systemprovides RF energy having voltage that increases over a minimal timeperiod resulting in the supplied RF energy with a voltage profile havinga steep slope or change rate. In accordance with various embodiments,the system seeks to continue to increase voltage of the RF energy toidentify or determine an RF output peak condition. In accordance withvarious embodiments, the RF output peak condition is denoted by amaximum current or power value resulting from the increasing voltage ofthe supplied RF energy. In various embodiments, the system seeks toincrease voltage of the supplied RF energy up to and/or equal to this RFoutput peak condition. However, determining this RF output peakcondition or point can vary based on tissue type and/or tissue volume incontact with the electrode or electrodes of the electrosurgicalinstrument. As such, the high voltage ramp or pulse provided by thesystem has a duration that is variable based on the tissue in contactwith the instrument rather than a static, fixed, or predefined value, asexemplified in FIG. 4 . Similarly, electrode size and electrode contactrelative to the tissue can further cause variations in this RF outputpeak condition. As such, determination of the RF output peak conditioncan be difficult.

With the system seeking to reach this varying RF output peak condition,the amount of time the system or electrosurgical generator supplies RFenergy can also vary. For example, as shown in FIG. 5 , the peakconditions 121 occur at different times with tissue of differentvolumes. For example, tissue with smaller volumes may experience theirrespective peak conditions much earlier within a seal cycle compared totissue that may have a much larger volume (e.g., as late as 1250 ms intoa seal cycle). As such, the peak condition in various embodimentsgenerally happens later for thicker tissue, as thicker tissues may takelonger to heat up. Furthermore, the height of the peak can be determinedby the surface area of the tissue. Tissues with larger surface areas mayhave higher peak values due to having more tissue being or acting aselectrically parallel resistance. In various embodiments, however, theamount of time for quickly increasing the voltage of the RF energy beingapplied to the tissue is limited to a set maximum time threshold orlimit and as a result avoids applying the RF energy longer thannecessary. Setting a static time without seeking to reach the RF outputpeak condition however can lead to applying the RF energy longer thannecessary, particularly for small tissue volumes. Furthermore, the useof static times can also present the situation where applying RF energymay not be long enough, particularly for large tissue volumes.

Accordingly, in accordance with various embodiments, providing a dynamicvoltage ramp balances system performance on each end and allows for aclose-to-ideal or optimal RF energy dosage initially or early andultimately resulting in optimal tissue sealing. Rapidly achieving thisRF output peak condition optimizes overall sealing of tissue and reducestime to seal without losing or reducing tissue integrity. In accordancewith various embodiments, the electrosurgical generator initiallyadjusts the voltage of the RF energy to be relatively high (e.g., 40% orgreater than the maximum voltage) and increases the voltage of the RFenergy quickly (e.g., at a rate 10 volts per millisecond) to providethis dynamic voltage ramp or pulse to achieve the RF output peakcondition.

Using a dynamic ramp ensures any tissue, regardless of volume, forexample, is brought to the same RF output peak condition or watervaporization point quickly. As such, the likelihood of failing to reachor maintain the water vaporization point of the tissue (under-pulsing)is reduced. By reducing the likelihood of under-pulsing, the average RFdelivery after the pulse can be shortened in time or lowered in powerwithout affecting seal quality. Furthermore, the focus or attention ofthe system can be directed to removing water from the tissueefficiently, rather than variability associated with heating tissue.

As previously noted, determining when the RF output peak conditionoccurs is difficult, particularly in real-time. Noise or similarfluctuations or imprecision in measurement of the RF output may obscureor delay the determination of the RF output peak condition. Smoothing orfiltering out such imprecisions, in various embodiments, can assist inenhancing detection or determination of the RF output peak condition.Delays in filter processing and the like in various embodiments mayhowever also delay the determination of the RF output peak condition.Delays in identifying the determination of the RF output peak conditioncan cause the system to over-pulse the tissue.

In accordance with various embodiments, to avoid or reduce this delay inidentifying the RF output peak condition or a potential over-pulse ofthe tissue, the system can provide a break system. The break systemutilizes a break value defined based on a predicted maximum value orwindow representing the RF output peak condition. In variousembodiments, the break value is as a percentage of the predicted maximumand/or a static threshold or gap, e.g., 400 mA or 30 W, below or withina predicted maximum value or window. The system monitors the RF output,e.g., the current and/or power, and the break system ensures that themonitored current and/or power reaches this break value before thevoltage is adjusted, e.g., dropped, to ensure the RF output peakcondition is quickly and accurately identified, thereby balancing bothinterests. It is however recognized that the lower or greater offset ofthe break value below the predicted maximum, the longer the specificallyhigh voltage of the RF output is applied, e.g., over-pulse, but the lesslikely the system is to prematurely halt or drop the voltage of the RFoutput, e.g., under-pulse, due to for example triggering on noise.

In various embodiments, the system records or stores a predicted maximumvalue and looks for the next monitored value to exceed the storedpredicted maximum value. When this occurs, the monitored value is storedas the “new” maximum value. In various embodiments, the system monitorsor records the RF output at set intervals, such as every 50 ms, andcompares the interested value of the RF output against the storedpredicted maximum value to determine if a new maximum has occurred.

In accordance with various embodiments, the system utilizes a series ofstates with exit conditions set at regular intervals. As RF energy isapplied and the value of interest changes, e.g., power and/or currentincreases, states are progressed through or cascaded. By increasing thenumber of states, the resolution of the cascade increase. However,depending on the resolution of the cascade, some accuracy can be lost indetermining the RF output peak condition. A cascade or similarprogression of states however is computationally less intensive and doesnot require or minimize the use of variables.

In accordance with various embodiments, the break value or range iscalculated from a predicted maximum value by multiplying the predictedvalue by a percentage, e.g., 80%. Higher predicted maximums couldrequire a larger drop in the interested value (e.g., current or power)to trigger or to identify the RF output peak condition. A break value orrange in various embodiments is calculated from the predicted maximumvalue and subtracting a static offset (e.g., 400 mA or 30 W). Dependingon the predicted maximum, this can be result in smaller or larger valuesthan a percentage calculation but can be useful when the amplitude ofnoise or similar imprecision in the system is known, as the offset canbe set to account for the imprecision (e.g., set higher than theamplitude of the noise). To ensure that a peak is detectable, theinterested value (e.g., current or power) can be checked against thebreak value—in some scenarios the interested value (e.g., current orpower) must reach at least the break value prior to any adjustments tothe voltage to ensure that a peak can be identified. In variousembodiments, the system provides a combination of the offset andpercentage acting in parallel or serially and/or varying the order toenhance the identification or determination of the RF output peakcondition to, for example, account for known imprecisions or when thepredicted maximum value reaches a specific threshold where a larger dropin the interested value to trigger is not desired.

In various embodiments, the system monitors a rate of change of theinterested value (e.g., current and/or power) to determine or toanticipate the RF output condition. As such, the system monitors thederivative or rate of the interested value and a change (e.g., areduction in the change or rate) to identify the RF output peakcondition or an indication that the RF output peak condition is near orclose to occurring.

In various embodiments, the system is arranged to adjust the current ofthe RF output to determine the RF output peak condition. In particular,the system, e.g., the RF amplifier of the generator, gradually ramps upcurrent of the supplied RF energy and the generator is placed in currentregulation. When a current regulation value exceeds the tissue's abilityto take more current, the system will no longer be current regulated,resulting in a sharp increase in voltage as the system switchesregulation. This voltage condition is thus used as an indication ordetermination of the RF output peak condition. As such, this systemregulation can forgo the use of a predicted maximum value of interestbeing stored or utilized as provided in the percentage or offset systemsor processes.

In various embodiments, if errors or an unexpected result occurs, thesystem terminates the process, e.g., the supplying of the RF energy. Invarious embodiments, such errors comprise a short detection error oropen detection error. In one embodiment, a short detection error isdetermined by the electrosurgical generator when a measured phase angleof the supplied RF energy by the electrosurgical generator equals orexceeds a predetermined value, e.g., sixty degrees. In one embodiment,an open detection error is determined by the electrosurgical generatorwhen a measured current of the supplied RF energy equals or is below apredetermined value, e.g., 100 milliamps, and/or a measured voltage ofthe supplied RF energy equals or exceeds a predetermined value, e.g., 50volts. Completion of the control process without errors indicates asuccessful tissue seal. A successful tissue seal in accordance withvarious embodiments is recognized as the tissue seal being able towithstand a predetermined range of burst pressures or a specificthreshold pressure.

In accordance with various embodiments, it has been identified thattissue seal formation is dependent on denaturization and cross linkageof the native collagen present in vasculature extra cellular matrixwhich starts at about 60° C. The strength of this matrix is highlydependent on desiccation (or removal of moisture) at the seal site viavaporization of the water present in the sealed tissue. Additionally, ata temperature of at least 80° C., bonds between the denatured collagenand other living tissues can be created. Furthermore, that collagendegrades in response to duration under elevated temperature rather thanthe peak temperature of exposure. As such, exposing tissue to hightemperature conditions (e.g., 100° C.) for the duration of a relativelyshort seal cycle does not impact the structure of the collagen butallows for the vaporization of water. The total time to seal tissue, inaccordance with various embodiments, is reliant on heating the structureto the high temperature, e.g., 100° C., to vaporize water such that thedenatured collagen crosslinks and bonds to tissue and to limitcollagen-water hydrogen bonding. To optimize seal time, it was thereforefound to be desirable to achieve 100° C. within the grasped tissue asquickly as possible to begin the desiccation process.

As such, in accordance with various embodiments, after RF energy hasbeen initiated and/or various device checks are performed, theelectrosurgical generator employs through the supplied RF energy adynamic voltage ramp. Once the dynamic voltage ramp is complete, thesystem reduces the voltage to a predetermined level and slowly ramps upthe voltage of the supplied RF energy. While the ramp occurs, sufficientamount of power is applied to the tissue to maintain a temperaturesufficient for desiccation. This allows for continuous vaporization at arate that does not cause seal structural failures and enhances vesselsealing performance.

In an embodiment, the application of high voltage levels may cause thesealed tissue to adhere to the active electrodes. As such, terminationof the voltage ramp at a lower peak voltage and holding that voltageoutput constant at the end allows for continued energy application whilereducing the potential for tissue adherence to the active electrodes.Determination of when to terminate the voltage ramp, in accordance withvarious embodiments, is conducted by monitoring the phase and current ofthe supplied RF energy. As the tissue desiccates, the phase will becomemore capacitive and will draw less current. By terminating the voltageramp at a fixed current value as it falls and when the phase iscapacitive, the desiccation level of the tissue can be categorized. Thisvariable voltage set point allows the seal cycle to adjust the energyapplication based on electrical and structural differences in tissuesbeing sealed.

In various embodiments, in order to achieve the appropriate tissueeffect, the phase angle, current, and/or power of the applied RF energyare measured, calculated, and/or monitored. FIG. 4 to FIG. 7 providegraphical representations of exemplary seal cycles in accordance withvarious embodiments. As illustrated in FIG. 7 , voltage 111 a is shownrelative to other RF output readings or indicators such as power 111 b,impedance 111 c, energy 111 d, current 111 e, and phase 111 f.Additionally, although shown in FIG. 4 to FIG. 7 , in variousembodiments, the electrosurgical generator can be configured to notmeasure or not calculate one or more of the indicators or readings(e.g., impedance) to reduce operational and power costs andconsumptions, and/or reduce the number of parts of the electrosurgicalgenerator. The additional information or readings are generally providedor shown for contextual purposes. Additionally, in various embodiments,impedance or temperature readings may not be used or may not be measuredbeing that such readings may be imprecise or impractical.

As shown in FIG. 7 , the voltage of the RF output 111 a is increased inthe initial moments of the seal cycle and for a period relatively shortcompared to the total seal time to generate the voltage ramp or pulse ofRF energy 131 (illustrated in FIG. 6 ). In accordance with variousembodiments, the system seeks to determine or reach the RF output peakcondition 121. Subsequently after reaching the RF output peak condition121, the voltage of the RF energy is reduced and ramped up, slowly,relative to the voltage pulse. In various embodiments, the slow voltageramp 132 by the system seeks to maintain the tissue between the jawsclose to at least 100° C. and thereby control the boiling rate of waterin the tissue. In accordance with various embodiments, in order toachieve the appropriate tissue effect of sealing the tissue, the phaseangle, current, and power of the applied RF energy are monitored.Voltage of the RF energy is then held constant 133 to reduce thepotential for tissue adherence. At seal completion (e.g., within apredetermined time frame or period according to the system), the RFenergy supplied by the system is terminated or the RF energy supply ishalted, disrupted, or stopped 134. In various embodiments, the voltageramp of the RF energy is terminated and after a predefined time periodaccording to the system, the RF energy supplied by the system isterminated or the RF energy supply is halted, disrupted, or stopped.

In various embodiments, the system identifies unintended current drawprovided, for example, in some tissue bundles that draw the maximumcurrent or power that can be supplied by the generator. While the systemis under such a current condition, the supply of RF energy required toseal the tissue may not be sufficient or be efficiently supplied by thesystem. In various embodiments, to handle such a condition, the systemdetermines if the current of the RF energy output is greater than 90% ofthe allowable maximum current, e.g., 4500 mA. If so, the system waits ordelays further to ensure that the current has sufficiently droppedthereby indicating that sufficient desiccation of the tissue hasoccurred. If, after such a delay, the current has not sufficientlydropped, an error is indicated and/or the RF energy being supplied ishalted. In accordance with various embodiments, the system determines orconfirms that the current has sufficiently dropped if the current fallsbelow a current threshold, e.g., 4100 mA. As such, the system determinesthat the current condition has ceased and/or the tissue reached avaporization or peak condition.

Referring now to FIG. 8 , in one embodiment, the electrosurgicalgenerator 10 is connected to AC main input and a power supply 41converts the AC voltage from the AC main input to DC voltages forpowering various circuitry of the electrosurgical generator 10. Thepower supply also supplies DC voltage to an RF amplifier 42 thatgenerates RF energy. In one embodiment, the RF amplifier 42 converts 100VDC from the power supply to a sinusoidal waveform with a frequency of350 kHz which is delivered through a connected electrosurgicalinstrument or tool 20. RF sense circuitry 43 measures/calculatesvoltage, current, power, and phase at the output of the electrosurgicalgenerator 10 in which RF energy is supplied to the connectedelectrosurgical instrument or tool 20. The measured/calculatedinformation is supplied to a controller 44.

In one embodiment, the RF sense 43 analyzes the measured AC voltage andcurrent from the RF amplifier 42 and generates DC signals for controlsignals including voltage, current, power, and phase that are sent tothe controller 44 for further processing. In one embodiment, RF sense 43measures the output voltage and current and calculates the root meanssquare (RMS) of the voltage and current, apparent power of the RF outputenergy, and the phase angle between the voltage and current of the RFenergy being supplied through the connected electrosurgical instrumentor tool 20. In particular, the voltage and current of the output RFenergy are processed by analog circuitry of the RF sense to generatereal and imaginary components of both voltage and current. These signalsare processed by a field-programmable gate array (FPGA) to givedifferent measurements relating to voltage and current, including theRMS measurements of the AC signals, phase shift between voltage andcurrent, and power. Accordingly, in one embodiment, the output voltageand current are measured in analog, converted to digital, processed byan FPGA to calculate RMS voltage and current, apparent power and phaseangle between voltage and current, and then are converted back to analogfor the controller 44.

In one embodiment, controller 44 controls or signals the RF amplifier 42to affect the output RF energy. For example, the controller 44 utilizesthe information provided by the RF sense 43 to determine if RF energyshould be outputted, adjusted or terminated. In one embodiment, thecontroller 44 determines if or when a predetermined current, power,and/or phase threshold has been reached or exceeded to determine when toterminate the output of RF energy. In various embodiments, thecontroller 44 performs a fusion or sealing process described in greaterdetail herein and in some embodiments the controller 44 receives theinstructions, settings, or script data to perform the sealing processfrom data transmitted from the electrosurgical instrument or tool 20.

The RF Amplifier 42 generates high power RF energy to be passed througha connected electrosurgical instrument or tool 20. In one example, theelectrosurgical instrument or tool 20 is used for fusing or sealingtissue. The RF Amplifier 42 in accordance with various embodiments isconfigured to convert a 100 VDC power source to a high power sinusoidalwaveform with a frequency of 350 kHz. The converted power is thendelivered to the connected electrosurgical instrument or tool 20. The RFSense 43 interprets the measured AC voltage and current from the RFamplifier 42 and generates DC control signals, including voltage,current, power, and phase, that is interpreted by the controller 44.

The electrosurgical generator 10 (which includes the controller 44and/or the RF sense 43) monitors and/or measures the RF energy beingsupplied to determine if it is as expected. In various embodiments, thesystem (e.g., the controller and/or RF sense), monitors the voltageand/or current of the RF energy to ensure the voltage and the currentare above predefined threshold values. The system (e.g., the controllerand/or RF sense), also monitors, measures, and/or calculates the phaseand/or power of the supplied RF energy. The system (e.g., the controllerand/or RF sense) ensures that the voltage, current, phase, and/or powerof the supplied RF energy is within a predefined voltage, current,phase, and/or power window or range. In one embodiment, the voltage,current, phase, and/or power window are respectively delimited by apredefined maximum voltage, current, phase, and/or power and apredefined minimum voltage, current, phase, and/or power. If thevoltage, current, phase, and/or power of the RF energy moves out of itsrespective window, an error is indicated. In one embodiment, therespective window slides or is adjusted by the system as RF energy isbeing supplied to seal the tissue between the jaws of the instrument.The adjustment of the respective window is to ensure that supplied RFenergy is as expected. The system, in various embodiments, monitors thephase, and/or current or rate of phase, and/or current of the suppliedRF energy to determine if the phase and/or current has reached orcrossed a predefined phase and/or current threshold. If the phase and/orcurrent crossing has occurred with respect to the predefined phaseand/or current threshold, then the RF energy is supplied for apredefined time period before terminating.

In accordance with various embodiments, an operations engine ofcontroller 44 enables the electrosurgical generator 10 to beconfigurable to accommodate different operational scenarios includingbut not limited to different and numerous electrosurgical instruments ortools, surgical procedures, and preferences. The operations enginereceives and interprets data from an external source to specificallyconfigure operation of the electrosurgical generator 10 based on thereceived data.

In accordance with various embodiments, the operations engine mayreceive configuration data from a database script file that is read froma memory device of the electrosurgical tool or instrument 20. Thedatabase script file defines the state logic used by the electrosurgicalgenerator 10. Based on the state determined and measurements made by theelectrosurgical generator 10, the database script file can define or setoutput levels as well as shutoff criteria for the electrosurgicalgenerator 10. The database script file, in one embodiment, includestrigger events that include indications of a short condition, forexample, when a measured phase is greater than 60 degrees, or an opencondition, for example, when a measured current is less than 100 mA.

In accordance with various embodiments, after the dynamic voltage ramp,tissue that draws a relatively low amount of current or power is smallin volume or may be already highly desiccated as shown, for example, inFIG. 9 . The highly desiccated tissue can be commonly encountered in adouble or repeated seal situation (e.g., when a surgeon activates theinstrument to supply RF energy a second time after a first seal cycle oran already completed seal cycle without moving the instrument orpositioning the instrument on different portions of the tissue or anentirely different tissue). Double or repeated seals results in anadditional application of RF energy including heat and thereby increasespotential eschar buildup, thermal spread, and/or adhesion. In variousembodiments, the system reduces or prevents RF output with a highvoltage when such repeated seals occur.

In accordance with various embodiments, the system identifies ordetermines a tissue's desiccation level in contact with the instrument.The system employs low levels of current or power, high levels ofimpedance, low phase angles, low energy delivery, and/or a lack of watervaporization (e.g., steam) during the seal cycle to identify a tissue'sdesiccation level. Once the desiccation level of the tissue has beenidentified, the RF output is reduced, such as providing RF energy for alimited time period or power level. In various embodiments, staticthresholds can be used for any of these values to trigger conditions(e.g., 500 mA) and/or thresholds can be calculated during the seal cycle(e.g., 20% below a predicted maximum).

In various embodiments, the system uses one or more of these thresholdvalues to distinguish already-sealed tissue and triggers early in theseal cycle. At the end of the seal cycle, first activations andsubsequent activations can look very similar with the tissue beingdesiccated in both cases. However, at the beginning of the seal cycle,first activations will draw much more current or power since water isstill present in the tissue (compared to subsequent seals which maynot). In addition, as tissue seals, the current or power drawn canchange substantially. An activation on an already-sealed tissue may havea much lower rate of change and as such, the system utilizes thederivative of measurement value of interest to be used to identify ameaningful change being made to the tissue.

In various embodiments, the system tracks phase of the RF output and inparticular, at the beginning of a seal cycle, to identify repetitiveseals and/or thin tissue. Double seals tend to have phase values ofgreater than 20 degrees. Once a repeated seal or piece of thin tissue isidentified, an alternate RF path for that tissue can be applied.

In various embodiments, the system uses a cascade of phase values whichadjusts the RF output depending on the magnitude of the initial phase.For example, if the phase is between 20 and 25 degrees, a modestreduction of RF energy is applied. However, if the phase is between 25and 30 degrees, there is more certainty of the type of tissue in contactwith the instrument, and thus RF energy being applied is reduced furtheror more aggressively. Continuing with this example, a phase angle over30 degrees would provide the largest or most aggressive reduction in RFenergy.

Once highly desiccated or thin tissue has been identified, any change inRF output that results in less heat being applied results in a bettertissue sealing effects. Additional RF energy or no reduction in RFenergy on this type of tissue can result in additional thermal spread,eschar, adhesion, and/or a longer procedure time without providingfurther benefits to hemostasis.

In accordance with various embodiments, the electrosurgical systemcomprising a double seal system that uses a threshold value to stop avoltage ramp, which results in in a lower hold voltage through the sealand/or uses a threshold value to terminate or halt the RF output and/orending the seal cycle. In various embodiments, the double seal systemalso uses a threshold value to immediately leave a state, rather thanreaching a timeout value and can result in a reduction in total sealtime.

Exemplary RF energy control process, script, or systems for theelectrosurgical generator and associated electrosurgical tools forfusing or sealing tissue in accordance with various embodiments areshown in FIG. 10 . In a first step 71, RF energy is supplied by theelectrosurgical generator through the connected electrosurgical tool.The electrosurgical generator sets the voltage of the supplied RF energyin order to generate the RF energy having a steep ramp in step 72. Inaccordance with various embodiments, the RF energy that is provided orgenerated is a steep ramp with voltage increasing from a predefinedinitial value (e.g., 40V) to a maximum value (e.g., 60V) in a predefinedtime period (e.g., 75 ms) and/or with current increasing from apredefined initial value (e.g., 2500 mA) to a predefined maximum value(e.g., 5000 mA) in the same predefined time period (e.g., 75 ms). Theelectrosurgical generator or system determines or identifies an RFoutput peak condition in step 73 while continuing to supply RF energy inthe ramping fashion performed in step 72.

In various embodiments, the system monitors or measures the currentand/or power of the RF output in order to determine if the currentand/or power is decreasing or has reached a predefined threshold. Thisis performed in order to further determine if a peak condition has beenreached. If a peak condition is not identified or reached, the systemdetermines if a double seal condition is present in step 74. In variousembodiments, the system monitors or measures the current of the RFoutput and determines if the current is decreasing or has reached apredefined current threshold to determine if a double seal condition ispresent or identified. If the peak condition and/or a double or repeatedseal is identified, the system alters or adjust to reduce the voltage ofthe RF output in step 75. In various embodiments, the system causes theRF energy to ramp gradually (in step 75), increasing from a predefinedinitial value (e.g., 35V) to a maximum value (e.g., 45V) over apredefined time period (e.g., 500 ms).

The electrosurgical generator or system monitors, determines, oridentifies a hold condition in step 76 while continuing to supply RFenergy in the ramping fashion as described in step 75 (above). Theelectrosurgical generator or system, in various embodiments, measures,calculates, and/or monitors at least the phase, voltage, current, power,and/or change/rate thereof of the supplied RF energy. If the condition(e.g., a phase and current condition) is reached or equals, exceeds orfalls below a predetermined threshold or value in step 76, the RF outputis adjusted in step 77. In various embodiments, the electrosurgicalgenerator causes the voltage of the supplied RF output to be heldconstant and/or the ramp terminated. In various embodiments, if a phasecondition or threshold is reached or falls below a predetermined phasethreshold value and a current condition or value is reached or fallsbelow a predetermined current threshold value, the electrosurgicalgenerator adjusts the voltage of the supplied RF energy to be constant.If the phase and current condition or threshold is not reached orcrossed, the electrosurgical generator waits a predefined time periodwhile continuing to supply RF energy in the ramping fashion (via step75) and monitoring for the hold condition (via step 76). With constantvoltage (via step 77), the electrosurgical generator monitors,identifies, or determines an end condition (via step 78) whilecontinuing to supply and/or adjust the RF energy being supplied (in step77). If the end condition is determined or identified, the process ischaracterized as being done. Termination procedures are initiated and/orRF energy supplied by the generator is stopped (in step 79). If thepower condition or threshold representing the end condition is reachedor equals, exceeds or falls below a predetermined threshold or value,the process is characterized as being done. Termination procedures canthen be initiated and/or RF energy supplied by the generator can bestopped. If the end condition or threshold is not reached or crossed,the electrosurgical generator continues to supply RF energy, whilemonitoring for the power condition.

In various embodiments, prior to the start of the process, impedance ismeasured to determine a short condition or open condition through a lowvoltage measurement signal delivered to a connected electrosurgicaltool. In one embodiment, passive impedance is measured to determine ifthe tissue grasped is within the operating range of the electrosurgicaltool (e.g., 2-200Ω). If the initial impedance check is passed, the RFenergy is supplied to the electrosurgical tool, after whichimpedance/resistance is not measured again or ignored.

In various embodiments, the maximum current or power value is static orpredetermined, stored in memory, or is provided or set through externalinputs. In accordance with various embodiments, the maximum current orpower value is determined by the system through the application of theRF energy and monitoring the current and/or power of the supplied RFenergy to determine a current or power peak. In various embodiments, themaximum current or power value represents a vaporization point for thetissue in contact with the electrosurgical instrument. In variousembodiments, the generator provides a high voltage steep ramp to bringthe tissue to a water vaporization point quickly.

In accordance with various embodiments, a maximum phase value isdetermined by the system through the application of the RF energy andmonitoring the phase to determine a phase peak representing an RF outputpeak condition. In various embodiments, a thermocouple or similartemperature sensor or detection system is provided with the instrument,such as a thermocouple embedded on the surface of a jaw, to monitortissue temperature and potentially identify a rapid rise of temperatureoccurring until water vaporization begins, at which point a state changewould stop the rise in temperature due to additional heat creating steamand thus an RF output peak condition can be identified. In accordancewith various embodiments, a minimum impedance is determined by thesystem through the application of the RF energy and monitoring thetissue impedance to determine an impedance floor representing an RFoutput peak floor. As such, the process or system is somewhat invertedwith a minimum value or window being determined rather than a maximum.

In various embodiments, the electrosurgical generator provides a highvoltage ramp or pulse to bring the tissue to a RF output peak point orcondition quickly. In various embodiments, the RF output peak conditionrepresents or corresponds to a water vaporization point or condition,e.g., when the fluid in the tissue begins to change state and vaporize.This can be observed when steam starts being generated from the tissuebeing sealed. This point or condition, in various embodiments, isdefined or identified when the power or current output of the RF energybeing applied or supplied is at its greatest or reaches its peak. If thevaporization or peak point is not reached during the pulse (e.g.,under-pulsing), then the subsequent drop in voltage and gradual ramp-upis delayed in this seal cycle. Tissue that is under-pulsed starts itseffective seal cycle or removal of water much later than anticipated,resulting in less total water being removed in the same time period.

In accordance with various embodiments, the electrosurgical generator isconfigured to provide additional regulation of various parameters orfunctions related to the output of the RF energy, voltage, current,power, and/or phase and the operations engine is configured to utilizethe various parameters or functions to adjust the output of the RFenergy. In one exemplary embodiment, the control circuitry providesadditional regulation controls for direct regulation of phase in whichvoltage, current, and/or power output would be adjusted to satisfyspecified phase regulation set points provided by the operations engine.

In accordance with various embodiments, the generator utilizes themonitored, measured and/or calculated values of voltage, power, current,and/or phase (e.g., control indicators) to recognize and act/performoperation conditions. In various embodiments, additional measurements orcalculations based on the measured values related to RF outputregulation circuitry are provided by the script or operations engine torecognize and act upon additional or different events related to ortrigger by the additional measurements or calculations relative to othermeasurements or thresholds. The additional measurements in oneembodiment include error signals in combination with a pulse widthmodulation (PWM) duty cycle used to regulate the output of voltage,current and/or power or other similar regulation parameters. Differentor additional events or indicators that could be identified andtriggered in various embodiments could be transitions from oneregulation control to another regulation control (e.g., currentregulation to power regulation). In various embodiments, subsequentimpedance or temperature checks or measurements may not be performed assuch checks or measurements may be imprecise and/or impractical.

In various embodiments, the generator utilizes many states, controlpoints, or checks to identify a phase, current, or power value andrespectively for a positive or negative trend. An error is signaled ifthe electrosurgical generator does not identify an expected trend. Themultistate checks increase or enhance the electrosurgical generatorresolution in identifying an expected RF output trend over differenttypes of tissue.

In various embodiments, the electrosurgical generator also monitors thephase or current and/or rate of phase or current to determine if theconnected electrosurgical tool has experienced an electrical opencondition or short condition. In one example, the electrosurgicalgenerator identifies an electrical short condition of the connectedelectrosurgical instrument by monitoring the phase of the applied orsupplied RF energy. If the monitored phase is greater than a predefinedmaximum phase value, an electrical short condition is identified.Similarly, in one example, the electrosurgical generator identifies anelectrical open condition of the connected electrosurgical instrument bymonitoring the current of the applied or supplied RF energy. If themonitored current is less than a predefined minimum current, anelectrical open condition is identified. In either or both cases, theelectrosurgical generator upon discovery of the open condition and/orshort condition indicates an error and the RF energy being supplied ishalted.

In various embodiments, the predefined process as described throughoutthe application is loaded into a memory module embedded into a connectorremovably connected to a plug and/or cable connection to anelectrosurgical instrument. In various embodiments, the device script orprocess is programmed onto an adapter PCBA (Printed Circuit BoardAssembly) contained within the device connector or hardwired intocircuitry within the device connector or controller duringmanufacture/assembly. The script source file is written in a customtext-based language and is then compiled by a script compiler into ascript database file that is only readable by the generator. The scriptfile contains parameters specifically chosen to configure the generatorto output a specific voltage (e.g., 100 v (RMS)), current (e.g., 5000 mA(RMS)), and power level (e.g., 300 VA). In various embodiments, a devicekey programmer device reads and then programs the script database fileinto the memory of the adapter PCBA.

Turning now to some of the operational aspects of the electrosurgicaltool or instrument described herein in accordance with variousembodiments, once a vessel or tissue bundle has been identified forfusing, the first jaw 31 and the second jaw 33 are placed around thetissue. The movable handle 23 is squeezed and thereby pivots the firstjaw 31 and the second jaw 33 together to effectively grasp the tissue.The actuator 24 has a first or initial position in which the jaws 22 arein an open position with the movable handle 23 positioned away or spacedfrom the stationary housing 28.

The depression of the activation button 29 by the surgeon causes theapplication of the radio frequency energy to the tissue between the jaws22. Once the tissue has been fused, the actuator 24 can be reopened bythe movable handle 23 being released and moved away from stationaryhousing 28. To cut tissue between the jaws 22, the user can actuate theblade trigger 25. When the blade trigger is moved proximally, a cuttingblade moves distally to divide the tissue between the jaws 22. When thesurgeon releases the blade trigger 25, the blade spring resets thecutting blade to its original position. In accordance with variousembodiments, the actuator 24 has a cut position in which the jaws 22 arein a closed position, the movable handle 23 is closed and latched andthe blade trigger 25 has been depressed advancing the cutting blade toits distal most position.

In various embodiments, an intermediate or unlatched position isprovided in which the jaws 22 are in a closed or proximate position butthe movable handle 23 is unlatched. As such, if the movable handle 23 isreleased, the movable handle 23 will return to its original or initialposition. In one embodiment, the blade trigger 25 may not be activatedto cut tissue between the jaws 22 but the activation button or switch 29may be activated to fuse tissue between the jaws 22. In variousembodiments, a latched position is provided in which the jaws 22 are ina closed or proximate position and the movable handle 23 is latched. Assuch, if the movable handle 23 is released, the movable handle 23 willnot return to its original or initial position. In one embodiment, theactivation button or switch 29 may be activated to fuse tissue betweenthe closed jaws 22 and/or the blade trigger 25 may be activated to cuttissue between the jaws 22.

As described, in accordance with various embodiments, theelectrosurgical instrument has a first (open) state in which the jaws 22are spaced from each other and thus the movable handle 23 is also spacedfrom the stationary housing 28. The electrosurgical instrument is thuspositioned to grasp tissue between the jaws 22. In the second(intermediate) state of the instrument, the jaws 22 are proximate toeach other to grasp tissue between the jaws 22 and likewise the movablehandle 23 and the stationary housing 28 are proximate to each other. Thesurgeon can revert back from the second state to the first state byopening the jaws 22 and thus positioning the jaws 22 again to grasp thetissue or other tissue. In the third (closed) state of theelectrosurgical instrument, the movable handle 23 is moved furthercloser to the stationary housing 28. In some embodiments, the movablehandle 23 may latch to the stationary housing 28. Movement to the thirdstate, tissue grasped between the jaws 22 can be cut through theactivation of the blade trigger 25. Movement to the third state, inwhich the movable handle 23 is latched to the stationary housing 28,reduces the potential situations whereby the tissue is unintentionallyreleased. Also, inadvertent cutting of tissue or cutting of tissue alongthe wrong tissue lines can be better avoided. Additionally, the third(closed) state allows the application of constant and continuouspredefined compression or range of compression on the tissue between thejaws 22 before, during, and after the activation of the RF energy,thereby enhancing the sealing or fusion of the tissue between the jaws22. In accordance with various embodiments, application of the RF energycan occur once the mobile handle 23 and jaws 22 are in at least thesecond state and once the activation button 29 is activated by thesurgeon. In some embodiments, the application of the RF energy can occurwhen the mobile handle 23 and jaws 22 are in the third state and oncethe activation button 29 is activated by the surgeon.

It is noted that in various embodiments to avoid false readings, theelectrosurgical generator does not measure resistance or impedance ofthe tissue during the supply of the RF energy to the tissue. Inaccordance with various embodiments, an electrosurgical system isprovided that decreases thermal spread and provides efficient powerdelivery for sealing vessels or tissue in contact with a bipolarelectrosurgical instrument through the controlled and efficient supplyof RF energy.

As described throughout the application, the electrosurgical generatorsupplies RF energy to a connected electrosurgical instrument. Theelectrosurgical generator ensures that the supplied RF energy does notexceed specified parameters and detects faults or error conditions. Invarious embodiments, an electrosurgical instrument provides the commandsor logic used to appropriately apply RF energy for a surgical procedure.An electrosurgical instrument for example includes memory havingcommands and parameters that dictate the operation of the instrument inconjunction with the electrosurgical generator. For example, theelectrosurgical generator can supply the RF energy but the connectedelectrosurgical instrument decides how much or how long the RF energy isapplied. The electrosurgical generator, however, does not allow thesupply of RF energy to exceed a set threshold even if directed to by theconnected electrosurgical instrument thereby providing a check orassurance against a faulty instrument command.

As described generally above and described in further detail below,various electrosurgical instruments, tools, or devices can be used inthe electrosurgical systems described herein. For example,electrosurgical graspers, scissors, tweezers, probes, needles, and otherinstruments incorporating one, some, or all of the aspects discussedherein can provide various advantages in an electrosurgical system.Various electrosurgical instruments and generator embodiments andcombinations thereof are discussed throughout the application. It iscontemplated that one, some, or all of the features discussed generallythroughout the application can be included in any of the embodiments ofthe instruments, generators and combinations thereof discussed herein.For example, it can be desirable that each of the instruments describedinclude a memory for interaction with the generator as previouslydescribed and vice versa. However, in other embodiments, the instrumentsand/or generators described can be configured to interact with astandard bipolar radio frequency power source without interaction of aninstrument memory. Further, although various embodiments may bedescribed in terms of modules and/or blocks to facilitate description,such modules and/or blocks may be implemented by one or more hardwarecomponents, e.g., processors, Digital Signal Processors (DSPs),Programmable Logic Devices (PLDs), Application Specific IntegratedCircuits (ASICs), circuits, registers and/or software components, e.g.,programs, subroutines, logic and/or combinations of hardware andsoftware components. Likewise, such software components may beinterchanged with hardware components or a combination thereof and viceversa.

Further examples of the electrosurgical unit, instruments andconnections there between and operations and/or functionalities thereofare described in U.S. patent application Ser. No. 12/416,668, filed Apr.1, 2009, entitled “Electrosurgical System”; Ser. No. 12/416,751, filedApr. 1, 2009, entitled “Electrosurgical System”; Ser. No. 12/416,695,filed Apr. 1, 2009, entitled “Electrosurgical System”; Ser. No.12/416,765, filed Apr. 1, 2009, entitled “Electrosurgical System”; Ser.No. 12/416,128, filed Mar. 31, 2009, entitled “Electrosurgical System”;and Ser. No. 14/848,116, filed Sep. 8, 2015, entitled “ElectrosurgicalSystem”; the entire disclosures of which are hereby incorporated byreference as if set in full herein. Certain aspects of theseelectrosurgical generators, tools and systems are discussed herein, andadditional details and examples with respect to various embodiments aredescribed in US Provisional Application Nos. 61/994,215, filed May 16,2014, entitled “Electrosurgical Fusion Device”; 61/944,185, filed May16, 2014, “Electrosurgical Generator with Synchronous Detector”;61/994,415, filed May 16, 2014, “Electrosurgical System”; and61/944,192, filed May 16, 2014, entitled “Electrosurgical Generator”,the entire disclosures of which are hereby incorporated by reference asif set in full herein.

The above description is provided to enable any person skilled in theart to make and use the surgical devices and perform the methodsdescribed herein and sets forth the best modes contemplated by theinventors of carrying out their inventions. Various modifications,however, will remain apparent to those skilled in the art. It iscontemplated that these modifications are within the scope of thepresent disclosure. Additionally, different embodiments or aspects ofsuch embodiments may be shown in various figures and describedthroughout the specification. However, it should be noted that althoughshown or described separately each embodiment and aspects thereof may becombined with one or more of the other embodiments and aspects thereofunless expressly stated otherwise. It is merely for easing readabilityof the specification that each combination is not expressly set forth.Also, embodiments of the present invention should be considered in allrespects as illustrative and not restrictive.

1. (canceled)
 2. An electrosurgical generator for fusing or sealingtissue comprising: a controller configured to: determine one or morecharacteristics related to an area of tissue, instruct an RF amplifierto generate a pre-determined amount of RF energy for an area of tissuebased on the determined one or more characteristics, detect changes tothe one or more characteristics for the area of tissue, and modify thepre-determined amount of RF energy based on the detected changes to theone or more characteristics; and an RF amplifier configured to generatean amount of RF energy that is passed to an electrosurgical instrumentconnected to the electrosurgical generator, wherein the amount of RFenergy generated is based on the instructions provided by the controllerto generate the pre-determined amount of RF energy.
 3. Theelectrosurgical generator of claim 2, wherein the pre-determined amountof RF energy being generated by the RF amplifier is for a pre-determinedperiod of time.
 4. The electrosurgical generator of claim 3, wherein theRF amplifier terminates generation of the RF energy to theelectrosurgical instrument after the pre-determined period of time. 5.The electrosurgical generator of claim 2 further comprising a userinterface configured to receive user input, wherein the user input isimplemented into instructions generated for the RF amplifier thatmodifies the amount of RF energy being generated.
 6. The electrosurgicalgenerator of claim 2, wherein the amount of RF energy generated by theRF amplifier is based on a type of electrosurgical instrument connectedto the electrosurgical generator.
 7. The electrosurgical generator ofclaim 2, wherein the one or more characteristics used by the controllerto generate instructions for the RF amplifier is based on associatedsurgical procedures being performed.
 8. The electrosurgical generator ofclaim 2, wherein at least one of the characteristics related to the areaof tissue is a desiccation level of the area of tissue.
 9. Theelectrosurgical generator of claim 8, wherein determination of thedesiccation level of the area of tissue is performed by evaluating anamount of steam being generated during a seal cycle from the area oftissue.
 10. The electrosurgical generator of claim 8, whereindetermination of the desiccation level of the area of tissue isperformed by using low levels of current or power during a seal cyclefrom the area of tissue.
 11. The electrosurgical generator of claim 10,wherein determination of the desiccation level of the area of tissue isbased on pre-determined thresholds associated with an amount of currentor power being drawn to distinguish between already-sealed tissue andtissue not yet sealed.
 12. The electrosurgical generator of claim 8,wherein determination of the desiccation level of the area of tissue isperformed by using high levels of impedance during a seal cycle from thearea of tissue.
 13. The electrosurgical generator of claim 8, whereindetermination of the desiccation level of the area of tissue isperformed by using low phase angles during a seal cycle from the area oftissue.
 14. The electrosurgical generator of claim 8, whereindetermination of the desiccation level of the area of tissue isperformed by using low energy delivery during a seal cycle from the areaof tissue.
 15. The electrosurgical generator of claim 2, wherein amagnitude of a modification of the pre-determined amount of RF energy isbased on different thresholds of the detected changes.
 16. Theelectrosurgical generator of claim 2, wherein determining one or morecharacteristics related to the area of tissue includes calculating an RFoutput peak condition corresponding to a maximum current or power valueresulting from an increasing voltage from the RF energy being suppliedto the area of tissue.
 17. The electrosurgical generator of claim 2wherein the controller is configured to further detect one or moreerrors, and wherein detection of at least one error results ininstructing the RF energy to terminate generation of RF energy to thearea of tissue.
 18. The electrosurgical generator of claim 17, whereinthe one or more errors include a short detection error and an opendetection error.
 19. The electrosurgical generator of claim 2, whereinat least one of the characteristics related to the area of tissue is atemperature, and wherein the controller is configured to maintain thetemperature of the area of tissue at 100° C.
 20. The electrosurgicalgenerator of claim 2, the controller is configured to download a scriptthat configures the electrosurgical generator for a particular surgicalprocedure, wherein the script is stored in a memory storage deviceassociated with the electrosurgical instrument.
 21. The electrosurgicalgenerator of claim 2, wherein the controller is further configured toidentify a current peak condition, the current peak condition beingidentified by: establishing a break value that is based on a percentageof a maximum amount or window for a voltage measurement or a currentmeasurement associated with the amount of RF energy that can be appliedto the area of tissue; and detecting that the voltage measurement or thecurrent measurement for the amount of RF energy being applied to thearea of tissue is greater than the break value.